Vehicles systems receive various operator commands in order to facilitate operator control of the powertrain, including an accelerator foot pedal input. Further, the relationship between the amount of operator depression and the powertrain response can be tuned to provide different drive feel and performance, and can be adjusted based on various engine or vehicle operating conditions. However, there may be conflicting goals in tuning the pedal relationship to vehicle output response based on numerous factors.
For example, a higher gain relationship may be desired for some lower pedal depression and/or lower vehicle speed conditions to provide a more “peppy” vehicle feel. This can be especially true when a vehicle is designed with a more under-powered powertrain in order to increase fuel economy and/or reduce emissions. In other words, a smaller engine and/or otherwise adjusted transmission may provide improved fuel economy, but may feel sluggish during acceleration driver tip-ins from lower speeds.
On the other hand, a lower gain relationship may be desired for other lower pedal depression and/or lower vehicle speed conditions to provide finer engine and/or vehicle output torque control to give the operator improved ability in torque selection and adjustment. This can be especially true during driving maneuvers under increased traffic conditions and/or during maneuvers such as vehicle parking or traversing rough terrain.
These and other issues may be at least partially resolved by adjusting a relationship between pedal input and vehicle output using an indication of environmental and/or traffic conditions. For example, by considering a distance to a forward vehicle indicative of vehicle traffic conditions, the gain may be adjusted to enable both a peppy feel during lower traffic conditions and a finer torque selection during higher traffic conditions. The distance to a forward vehicle may be provided by information already available in some adaptive cruise control systems, and thus such information may advantageously be used even during non-cruise control conditions.
Likewise, a driver may also provide some selectivity based on a desired fuel economy performance, such as through a driver selectable fuel economy switch, as to how the gain is adjusted in response to such information, thereby providing gain adjustment that is more sensitive to driver needs and/or goals. In one embodiment, by integrating gain adjustment using both environmental information and driver selectable fuel economy information, it may be possible to provide improved drivability over a variety of conditions while providing the operator with desired fuel economy performance in a smooth and coordinated way.
Note that the relationship between driver pedal input and vehicle and/or engine output may be adjusted in a variety of ways, including gradually adjusting the relationship over time, as well as further adjusting the relationship based on various operating parameters such as engine speed, vehicle speed, gear ratio, etc. Further, gain adjustment may include adjusting software-based transfer functions, algorithms, analog circuitry, signal processing, and/or combinations thereof.